Traffic information and management systems have been developed, wherein vehicles are used as probes for measuring traffic conditions in real-time. In these configurations, individual vehicles provide “floating car data,” such as, for example, the current time, speed, position, and heading of the probe vehicle, which can then be used to estimate travel time or traffic speed. These data are typically used as an online indicator of road network status, as a basis for detecting incidents, or as input for a dynamic route guidance system.
These systems generally include a traffic information center (TIC); a plurality of probe vehicles; technology for determining the location of each vehicle, such as, for example, the Global Positioning System (GPS), a system using cellular telephones, or a system using radio-frequency identification (RFID); and wireless communication means for allowing bilateral communication between the probe vehicles and the TIC. The TIC (or receiving center) receives and processes the data generated by the probe vehicles to determine a desired outcome or condition, and returns the result to a plurality of receiving vehicles that may further include partially implemented non-probe vehicles.
Conventional probe-vehicle systems, however, present various scalability concerns resulting from independent vehicle interaction with the center. Often, an exceedingly large number of probe vehicles redundantly communicate with the receiving center in order to provide a relatively small amount of useful data. For example, where a plurality of probe vehicles are located within a traffic jam, each vehicle may independently communicate with the center to redundantly alert the system to the presence of the traffic jam. Similarly, independent interaction can result in the omission of traffic conditions that do not involve probe vehicles; as is the case, for example, where the probe vehicles are spaced from the traffic jam and fail to communicate its presence to the center.
Another scalability concern is presented by the exceedingly large number of communication channels, one for each independently operating probe vehicle, that is needed to accommodate the frequent data communications. Finally, the large volume of incoming data that must be processed in real-time requires that there be substantial and constantly increasing capacity at the center.
These concerns, among others, result in the need for a more efficiently operating traffic information system that reduces communication volume, and thereby, reduces the required capacity of the system.